<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title></title>
	<style>
		.father{
			height: 300px;
			background: red;
			margin: 20px;
			overflow: hidden;
		}

		.son{
			height: 200px;
			background: blue;
			margin: 30px;
		}
	</style>
</head>
<body>
	<div class="father">
		<div class="son"></div>
	</div>
</body>
</html>